Specify connector version when initializing a cluster with 'clusters.create' API

I am using the clusters.create API in Python to create clusters in Dataproc.

{
 "projectId": "my-project-id",
 "clusterName": "example-cluster",
 "config": {
"configBucket": "",
"gceClusterConfig": {
  "subnetworkUri": "default",
  "zoneUri": "us-central1-b"
},
"masterConfig": {
  "numInstances": 1,
  "machineTypeUri": "n1-standard-4",
  "diskConfig": {
    "bootDiskSizeGb": 500,
    "numLocalSsds": 0
  }
},
"workerConfig": {
  "numInstances": 2,
  "machineTypeUri": "n1-standard-4",
  "diskConfig": {
    "bootDiskSizeGb": 500,
    "numLocalSsds": 0
  }
},
"initializationActions": [
  {
    "executableFile": "gs://cloud-example-bucket/my-init-action.sh"
   }
  ]
 }
 }

In gcloud shell the connector version and the executable files are specified as:

gcloud dataproc clusters create <CLUSTER_NAME> \
    --initialization-actions gs://dataproc-initialization- 
    actions/connectors/connectors.sh \
    --metadata 'gcs-connector-version=1.7.0' \
    --metadata 'bigquery-connector-version=0.11.0'

How to pass the connector versions (under metadata) to the API.

Running my script without passing the versions gives the following errors:

ERROR: None of connector versions are specified' ERROR: None of connector versions are specified + exit 1

The metadata field can be specified under config/gceClusterConfig as follows:

'config': {
        'gceClusterConfig': {
             "metadata": {
                 "bigquery-connector-version": "0.12.1",
                 "gcs-connector-version": "1.8.1"
                         }
                       }
          }